1. Field of the Invention
The present invention relates to a wireless communication system that transmits and receives information using polarization waves whose polarization angle varies.
2. Description of the Related Art
Toward the realization of sustainable development of society, high-efficiency operation of social infrastructure systems for producing and distributing, for example, energy, water, gas, petroleum and so forth is important. To this end, high-frequency operation of apparatus configuring the systems is required. In order to implement high-efficiency operation of apparatus configuring a system, a technology is considered promising that collects and analyzes a great amount of data obtained from a large number of sensors disposed in the individual apparatus configuring the system to estimate and predict an operational status and control information obtained on the basis of a result of the estimation is transmitted to the individual apparatus. Thus, a monitoring and controlling network for the technology is required.
In the monitoring and controlling network, a very great number of transmission paths are required for collecting data from the large number of sensors and transmitting control information to the individual apparatus. Therefore, a network configuration which uses a wireless communication technology suitable for a network having a great number of transmission paths is demanded.
Sensors disposed in an apparatus configuring a social infrastructure system and actuators for controlling the apparatus act themselves as electromagnetic wave scattering bodies. Therefore, in a wireless network that uses electromagnetic waves as a communication medium, it cannot be expected for a wireless device configuring the network to communicate in a line-of-sight state, and the network is operated in a special state in which it uses a non-line-of-sight wave for which a multiple reflection wave after reflection by the apparatus is used. As one of technologies for use in such a situation as just described, for example, a technology for implementing wireless communication of high reliability by a transmission antenna and a reception antenna of a small size under an environment in which interference by multipath waves occurs is disclosed, for example, in JP-2015-039218-A. The technology relates to a polarization angle division diversity wireless transmitter that includes modulation means for modulating an information signal of a first frequency with a second frequency and outputting a resulting first modulation signal, and electromagnetic wave transmission means for transmitting the first modulation signal in the form of two polarization waves independent of each other and superimposing a third frequency to the polarization waves.